Boiler tube slitter



sept. 23, 1947. H, F DUGGER` 2,427,843

BOILER TUBE SLITTER Filed March 2, 1945 Swan/whom Patented Sept. 23, 1947 UNITED STATES PATENT OFFICE BOILER TUBE SLITTER Horace F. Dugger, Charleston, S. C. Application March 2, 1945, Serial No. 580,694' i (Cl. Sli-91') 1 Claim. 1

This` invention relates-to tools for cutting tubes lengthwise, and more especially to tools useful for slitting tubes, such as boiler tubes, for removing them from their header plates.

An important object of my invention is to provide a tube cutting tool of the above character capable of being associated with a, pneumatic hammer whereby the tool is adapted to travel along the inside of a tube under the impact of the hammer and cut a recess in the wall ofthe tube.

Another object of my invention is to provide a tube cutting tool' of the above character comprising ay carrier block of approximately the same shape, but slightly smaller than the bore ofthe tube, and a cutting blade projecting laterally from one side thereof and adapted, during travel of the tool, to plow a recess in the wall of the tube and turn the chip of removed material inwardly of the tube.

Still another object of my invention is to provide a tube cutter of the above character in which the cutting blade is pivotally mounted on the carrier block so as to facilitate the withdrawal of the tool from the tube.

Other objects and advantages will be apparent from the following detailed 'description of a preferred embodiment of the invention, reference being had to the annexed drawing, in which:

Figure 1 is a longitudinal cross-sectional view through a, tube cutting tool showing the position it occupies with respect to a boiler tube preparatory to the cutting operation;

Figure 2 is a transverse cross-sectional view of the tool taken on the line 2-2 of Fig. l;

Figure 3 is a longitudinal cross-sectional view of the tool taken at right-angles to Fig. 1; and

Figure 4 is a View similar to that of Fig. 1 but showing the tool in the course of the cutting operation.

The form of tube cutting tool shown by the drawings comprises a carrier block I of substantially cylindrical shape and of a diameter approximating, but slightly smaller than, the inside of the boiler tube in which it is adapted to travel. The block is provided with a radially-disposed slot 2 extending from a position intermediate the length of the block and opening through the forward end or nose la of the block. As shown in Fig. 3, this slot is slightly flared outwardly toward the nose of the block. At the inner end of the slot-that is, at the end 2a of the slot remote from the nose la--a cutter blade 3 is pivotally mounted on a pin 4 transsecting the slot. The upper end of the blade is generally circular in shape and liessnugly within` acorrespondingly shaped pocket 2171 opening offffrom the slot2 adjacent its closed end; andthe other end of the blade projects radially outward beyond the circumference of theblock. The forward cutting side 3a ofthebladeis concavelycurved while its at rearward; side abuts against theinner end A2li of the slot, as shown ini-Figs. land i. Y

Extending from the rear end of the blockris a shank 5 of smaller diameter than the block. The outer end ofthe shank is formed with a head 6 adapted to be detachably held within a chuck 1 of a pneumatic hammer, one end' 8 of which is shown in Fig. 1.

The tool may be employed in the manner illustrated in Figs. 1 and 4 for removing a boiler tube B from a header plate 9a. The nose of the carrier block is first introduced into the end of the tube with the cutter blade 3 projecting beyond the slot into the position shown in Fig. 1. The cutter blade is of such length that its free end projects beyond the circumference of the carrier block a distance corresponding to the thickness of the wall of the tube 9. When the pneumatic hammer is set in operation, the carrier block is driven lengthwise within the tube under the impact of the hammer. The cutter blade, with its rear face solidly abutting the closed end 2a of the slot, plows a recess in the wall of the tube as the carrier block moves along the tube, and the chip I0 of material removed from the recess by the curved forward side 3a of the cutter blade is turned inwardly and forwardly of the slot 2, as indicated in Fig. 4. After the tube has been cut for a short distance beyond the header plate the tool may be withdrawn, the recessed end of the tube collapsed and the tube removed through the hole in the header plate.

When the tool is withdrawn from the tube, the blade 3, by virtue of its pivotal mounting on the pin 4, rocks backwardly into the slot 2 and thus is not required to retrace its path through the recess it h'as cut, such as would offer frictional resistance to the retraction of the tool. Because the chip removed by the cutting blade is directed inwardly and therefore presents no obstruction on the circumference of the tube, the tube may be readily withdrawn through its hole in the header plate. For the same reason, it is easy to start the cut, since the header plate embracing an end of the tube does not interfere with the removal of the chip, such as would be the case were the chip ejected outwardly of the tube. Because the carrier approximately fits the inside of the tube and because the top of the slot 2 is roofed 3 over, deformation of the tube is prevented and scarring or gouging of th'e header and the inside of the tube is avoided.

It will be apparent; that the stresses imposed upon the cutter blade are transmitted to the rear wall 2a of the slot and to the roof of the pocket 2b, thus relieving the pin 4 of excessive pressure such as might cause it to deform or break. Also, because the block substantially closes the interior of the tube, the chip plowed up in advance of the block is prevented from jamming into the slight clearance between the block and the wall of the tube.

My tubecutting tool is simple in construction and efficient in operation. No supplementary means are required for extending the cutting blade to, or maintaining it in, operating position. The tool is readily retractable from the tube and the tube slidably removable from its header plate at the conclusion of a cutting operation.

It is to be understood that the tube cutting tool described above is exemplary of a preferred embodiment of my invention and that various changes in the form, construction, arrangement and combination of the several parts may be made and substituted for those herein shown and described without departing from the nature and principle of my invention as defined by the following claim. y

I claim:

A tube cutting tool comprising a carrier block adapted to be inserted withina tube and corresponding in circumferential shape approximately to the inner circumferential shape of the tube, said block having a radially-disposed slot extendgage the wall of the tube, said blade having its forward face so shaped as to direct the chip of material removed from the tube inwardly of the tube, an arcuately-shaped pocket formed in the roof of the slot adapted to snugly receive the arcuate head of the blade, and a shank secured to and projecting from the rear end of the block adapted to be coupled to a, pneumatic hammer. HORACE F. DUGGER.

REFERENCES CITED The following references are of record in the le of this patent:

UNITED STATES PATENTS Number Name Date 1,070,750 Thumm Aug. 19, 1913 1,276,458 Wagner Aug. 20, 1918 1,315,865 Schanno Sept. 9, 1919 1,436,826 Schmidt Nov. 28, 1922 1,624,853 Winter Apr. 12, 1927 2,176,626 Gentry Oct. 17, 1939 

